Butanol is an important industrial chemical, useful as a fuel additive, as a feedstock chemical in the plastics industry, and as a foodgrade extractant in the food and flavor industry. Each year 10 to 12 billion pounds of butanol are produced by petrochemical means and the need for this commodity chemical will likely increase.
Microorganisms may be engineered for expression of biosynthetic pathways for production of butanols. Commonly owned and co-pending US Patent Application Publication US 20070092957 A1 discloses the engineering of recombinant microorganisms for production of isobutanol (2-methylpropan-1-ol). Commonly owned and co-pending US Patent Application Publication US20080182308A1 discloses the engineering of recombinant microorganisms for production of 1-butanol. Commonly owned and co-pending US Patent Application Publications US 20070259410A1 and US 20070292927A1 disclose the engineering of recombinant microorganisms for production of 2-butanol. Multiple pathways are described for biosynthesis of isobutanol and 2-butanol. The last step in all described pathways for all three products is the reduction of a more oxidized moiety to the alcohol moiety by an enzyme with butanol dehydrogenase activity. There are known alcohol dehydrogenases able to perform these conversions.
Additional enzymes with butanol dehydrogenase activity are desired for the production of butanols in recombinant host microorganisms engineered with a butanol biosynthetic pathway. Applicants have solved this problem by discovering an enzyme with butanol dehydrogenase activity in an environmental bacterial isolate, isolating the enzyme, and determining the encoding nucleic acid sequence from the identified Achromobacter xylosoxidans isolate.